Multiple pulse producing system



June 12, 1951 0.0. GRIEG ETAL 2,556,179

MULTIPLE PULSE PRODUCING SYSTEM Filed March 2, 1946 2 Sheets-Sheet l I 11/. mum:

JUPPL Y u 3d j? S m g 6 I 49 l 49 65 I :1 LiIIII 'I 1:11:11": I212: 57 f 54 INVENTORS 130M410 D. GW/EG ARA 0&0 M. ZEW/VE Patentecl June 12, 1951 UNIT STATES ATENT OFFICE MULTIPLE PULSE PRODUCING SYSTEM Application March 2, 1946, Serial 'No. 651,651

3 Claims.

This invention relates to multiple pulse producing systems and more particularly to systems for. producing multiplicity of pulse series of proper r. suitable shapes ,for the purpose of niodulation .or demodulation in the multiplex pulse time .circuit.

rSystems have been'proposed for multiplexing -pu1se circuits wherein the time division of the separatechannels is effected through means of ("an electronic distributor. tributorpreferably-comprises a cathode ray type distributor circuit wherein the beam is cyclically swept over a plurality of targets ordistributor This electronic disseg-ments. Each of the target electrodes may comprise a dynode .including separate .individual secondary electron emitting surfaces, and a common masking electrode to shield the beam from others of the target electrodes at the time it is iimpinging upon any one. --'has=been proposed particularlyin the demodulat- Such a type of tube ingv circuit of a time, pulse modulating system.

.In accordance'with our invention, we provide this type of tube for usein demodulating circuits of a system. Inthe outputof each separate target electrode, we provide. shaping networks to shape theoutput-pulses to thedesired form for use in such a system.

1 ,It is. an object of our invention to provide a simple system for producing and shaping pulses.

It :is a furtherobjectof our invention to provide an electronicdistributor with shaping means coupled to the output. of: each. distributor element to provide pulses of the desired shape.

It is .a still further .object of our invention to provide shaping means. to, form pulses into a predetermined shape having a substantially confstant finite slope and adjacent portions of substantially infinite slope.

I-t'is a still "further .obiectof our invention to ilproduce-pulse waves of desired shape for modulating or demodulating of pulse position sysso as effectively to vary the position of pulses in accordance with signals to be transmitted.

A feature of our invention includes means for so shaping the output pulses produced at the target electrodes that a wave having a constant slope portion will be produced. This may be accomplished most simply by providing a shaping circuit comprising a shunt condenser and resistor arrangement which will produce from the output pulses substantially triangular waves. v

According to a further feature-of our invention, we may provide a shaping circuit suitable for use in the output of a distributor of the type mentioned wherein each pulse is shaped to have a substantially infinite slope pedestal portion topped by a sawtooth triangular wave. At the upper edge of the sawtooth triangular wave is provided also a portion of substantially infinite slope. Thus, if a double gate clipper type of modulation is provided, the limits of time position of the pulse in the output thereof will be constant at points above and below the constant slope portion so that spreading out of the modulation pulses. beyond definite limits and consequent cross-talk maybe avoided.

While we have outlined above the general objectsand features of our invention, a better understanding thereof and a more complete explanationof how tomake and compound the invention as well as further features and objects thereof will be bestunderstood from the particular decription thereof made with reference to the accompanying drawings, in which:

vFig. 1 is a circuit diagram of a distributor and pulse clipping circuit incorporating the features of our invention;

Fig. 2 is a graphical representation showing curves helping to explain the operation of our sy em;

Rig. 3 illustrates amodified block circuit diagram of a shaping circuit made in accordance with the features of our invention; and

Fig. 4- is a schematic circuit diagram illustrating how the cross elements shown in Fig. 3 may be substantially. combined in a single circuit.

Turning first to Fig. 1, an electronic distributor tube is illustrated at' I. High voltage supply 2 and filament transform-er 3 furnish the operating potentials for distributor tube 5. Within the envelope of tube I is provided a conventional cathode 1 and concentrating grids 5 and 6 followed by the accelerating electrode i. As set of four deflecting plates is indicated at 8 coupled to beam centering resist-. ance elements 9. Two-phase energy from sup:-

3 ply source I is applied to deflecting plates 8 to produce cyclic rotation of the electron beam Within tube I. Preferably a voltage dividing resistor comprising resistance elements H, [2, l3 and 9 is connected to the negative pole of high voltage supply 2. Potentiometer resistors H and I2 are used to provide the desired voltage on grids and 6. Accelerating electrode 1 is coupled directly to the positive potential side of high voltage supply 2. Preferably the resistance voltage divider is grounded at M intermediate resistors l2 and I3. It has been found that this grounding helps prevent cross-talk in this type of distributor tube. An aperture plate I5 is provided coupled to the high voltage supply 2 and to one end of resistors 9. Opposite each aperture of plate [5 is provided individual target electrodes illustrated at i6, i7 and I8. These individual electrodes are coupled to individual output lines I9, and 2! respectively.

If the circuit is to be used as a distributor for modulation purposes, each of the output lines is provided with a modulator. Only one such modulator is indicated at 22 coupled to output line 2|. the type in which a variable position gate clipper is provided followed by a diiferentiating circuit so that output pulses timed with respect to the input voice signals may be produced. The

type of modulator forms no part of the present 5.

invention and has been illustrated merely in block form.

In order that waves, properly shaped for use in a circuit such as 22, may be provided, we prefer to include in the output circuit of each of the electrodes, shaping networks 23, 2d and 25, for example, which are connected to the respective lines I9, 20 and 2|. networks may comprise condenser-resistor combinations which will produce substantially triangular waves. 7

Turning to Fig. 2, a better understanding of the operation of the system may be had. Curves a and b of Fig. 2 illustrate output waves which may be obtained from two adjacent lines such as 20 and 2 i, for example. In the output of one of these lines, pulses are produced as shown at 26 and 2i which coincide in time with the impinging of the distributor beam on the target I'l. These pulses are substantially triangular in shape and the leading edge is shown particularly linear. In the modulator a gate clipper may be provided clipping the wave between levels 28 and 29. Signal modulation may serve to vary the level of gate clipper without changing the separation between levels 28 and 29 so that in accordance with the modulating signal the gate is varied up and down. Upon dilferentiation of the portion of the wave, included between the clipping levels, pulses may be produced having time positions variable in accordance with the level of the gate. It will be noted that in the succeeding line which may, for example, be line 2|, other pulses 38 may be produced, these pulses being time displaced with respect to pulses 26 in accordance with the time displacement caused by the electronic distributor. The gate clipper provided may be at a difierent level for this channel as indicated by lines 3 l, 32. It will be understood that as many circuits are to be provided as there are target electrodes in the distributor so that a multiple series of pulses may be produced in this fashion.

While we have shown in Fig. 1 the particular type of shaping circuit producing triangular waves such as shown in curves a and b of Fig. 2,

Modulator 22 may, for example, be of i As shown in Fig. 1, these it is clear that should the gate level be varied to a point below the lower end of pulses 26 or 30 or to a point thereabove, extraneous signals or distortion providing excessive pulse displacement might occur causing cross-talk between adjacent channels. In order to avoid this difficulty, a pulse shaping network may be provided to produce pulses shaped in accordance with curve I of Fig. 2. Such pulses will be seen to have a sloping portion 33 flanked by portions of substantially infinite slope as shown at 34 and 35. If, then, the clipping level adjustments 38 and 31 are advanced beyond the constant slope portion 33, no variation in pulse spacing will occur since the pedestal portion 34 and the extension portion 35 will serve to provide a pulse slice or portion to produce an input pulse at this time interval. The displacement, therefore, is limited between the two edges 34 and 35 and cannot be spread further to cause injurious cross-talk.

Turning to Fig. 3, there is shown a pulse shaping circuit which may be coupled in the output of each of the distributor electrodesof a. distributor such as shown in Fig. l for the purpose of providing waves substantially as shown in curve of Fig. 2. According to this arrangement a pulse source 38 produces substantially rectangular pulses. These pulses may be fed into a sawtooth pulse shaper 39 to produce an outputsawtooth pulse 49, to a differentiating circuit 4| to. produce substantially linear pulse 42 coinciding with one edge of sawtooth pulse and over a separate line 43 to provide properly timed pulse 44. These three pulse elements may be combined in a common mixer 45 to provide the output composite pulse 5%. It will be seen that pulse 46 has substantially the same shape as the composite pulse in curve I. Curves c, d and e illustrate more clearly how this composite pulse is formed. A rectangular pedestal portion 4'! is shown in curve 0, the triangular sawtooth portion 48 in curve d and the differentiated pulse portion 49 in curve e. It will be understood that in the mixer circuit, for example, the negative portion of the differentiated pulses of curve e may be eliminated. However, if these are not eliminated, this portion being negative will have no substantial affect on the pulses when passed through the individual modulators.

Fig. 4 illustrates a circuit arrangement which may incorporate the various elements of Fig. 3 substantially in a single circuit. In this circuit, tube 53 may, for example, be coupled to an'output distributor electrode of a tube such as shown in Fig. 1. In the load circuit of tube 50 is provided a composite network consisting of a resistor ele-' ment 5|, a condenser-resistor combination 52 and a differentiating coil 53. In resistor 5! the voltage drop of the rectangular wave applied to tube 5:] will produce a substantially rectangular wave portion 4'5 as illustrated. The condenser-resistor combination 52 will produce a sawtooth wave portion G8 as shown and the diiferentiating coil 53 will produce the pulses shown at 43. The out pu't voltage is taken across these elements resulting in a composite output pulse such-as shown at 1 While we have shown in Figs. 1 to 4 certain embodiments of our invention, it will be clear that many modifications will readily occur to those skilled in the art. Different types of shaping circuits may be provided as desired. More over, diiferent impedance combinations as shown in Fig. 4 may readily be provided to produce the desired composite pulses 46. Likewise, the tri'- angular pulses such as shown at 26, 21 and 30 (Fi 2) may be readily produced by other types of shaping circuits than the simple condenserresistor circuit shown in Fig. 1.

While the foregoing description sets forth our invention in what is at present considered the best way to make the units, it should be distinctly understood that this is given merely by way of example and is not to be considered as any limitation on the scope of our invention.

We claim:

1. A multiple pulse forming circuit, comprising an electron beam distributor provided with separate distributor segments for producing separate series of timed pulses, and individual shaper means operatively associated with each distributor segment for individually shaping the pulses of each series, said shaper means comprising means for producing a substantially rectangular pedestal :pulse, means for producing a sawtooth pulse of the same duration as said rectangular pulse, means for producing a substantially linear pulse coinciding substantially with one edge of said sawtooth and rectangular pulse, and means for combining said pulses into a composite pulse.

2. A system for providing base wave pulses for use in a pulse time modulating circuit comprising an electron beam distributor, separate targets for receiving energy pulses from the electron beam of said distributor, and shaping means for said pulses comprising means for producing a substantially rectangular pulse, means for producing a substantially sawtooth shaped pulse, means for producing a substantially linear pulse of substantially infinite slope, and means for combining said pulses to produce a composite pulse.

3. A system according to claim 2, wherein said shaping means includes an electron discharge tube, and a series circuit including said pulse producing means in the output circuit of said tube to produce and combine said pulses in a single circuit.

DONALD D. GRIEG. ARNOLD M. LEVINE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

